Science Sundays #6 – Tropical Cyclones: Hurricanes & Typhoons


Growing up, one of my biggest fears was tornadoes and thunderstorms. Some of my first memories of feeling genuine terror was tornado watches or warnings in the plains of Indiana or Northern Kentucky. The fact that they were natural disasters that forced us to remain in our basement until further notice made me feel powerless and frightened me. 

It took me until I understood how tornadoes formed and some sage advice from a relative – “You can’t worry about things out of your control” is still advice I forget all the time – until I wasn’t terrified of storms. Hurricanes (and typhoons) are different beasts, but they’re related and both are fascinating. I figured with Hurricane Florence in the news, now would be a good time to talk about how hurricanes form, and of course, as I mentioned in a previous post, why climate change is likely going to increase the devastation wrought by hurricanes. Compared to some of my previous posts, this one is going to be simpler and there’s not really else to say aside from the basics.

The Science

All about Tropical Cyclones

In the US, we often only talk about hurricanes hitting our mainland. Sometimes we’ll hear of typhoons hitting an island in the Pacific, which brings me to the difference between hurricanes and typhoons: the only difference is where they occur. Hurricanes form in the North Atlantic, central North Pacific, and eastern North Pacific, whereas Typhoons form in northwest Pacific; in the South Pacific and Indian Ocean, the generic term tropical cyclone is used.

Image courtesy of

Image courtesy of

According to NOAA:

A tropical cyclone is a generic term used by meteorologists to describe a rotating, organized system of clouds and thunderstorms that originates over tropical or subtropical waters and has closed, low-level circulation. 

The categories of a tropical cyclone are listed below, also from NOAA:

  1. Tropical Depression – <38 mph winds

  2. Tropical Storm – 39-73 mph winds

  3. Category 1 Hurricane/Typhoon – 74-95 mph winds

  4. Category 2 Hurricane/Typhoon – 96-110 mph winds

  5. Category 3 (major) Hurricane/Typhoon – 111-129 mph winds

  6. Category 4 (major) Hurricane/Typhoon – 130-156 mph winds

  7. Category 5 (major) Hurricane/Typhoon – >157 mph winds

“Hurricane season” is considered to be from June through November, and there are, on average, 12 hurricanes a year in the Atlantic basin. For a tropical cyclone to occur, there are two requirements: warm water (and I’ll get to this in a bit, but this is the part that climate change is altering) and “winds that don’t change much in speed or direction as they go up in the sky.”

The parts of a cyclone are below, from NASA:

Eye – “The eye is the "hole" at the center of the storm. Winds are light in this area. Skies are partly cloudy, and sometimes even clear.”Eye wall – “The eye wall is a ring of thunderstorms. These storms swirl around the eye. The wall is where winds are strongest and rain is heaviest.”Rain bands – “Bands of clouds and rain go far out from a hurricane's eye wall. These bands stretch for hundreds of miles. They contain thunderstorms and sometimes tornadoes.”

When cyclones hit land, water is pushed ashore; this is what’s called a storm surge, which is what combines with rain to cause flooding.

I’m sure most of us are familiar with the fact that cyclones are commonly named. This is so that it’s easier for people to discuss them and for scientists to track them. From NASA:

Each year, tropical storms are named in alphabetical order. The names come from a list of names for that year. There are six lists of names. Lists are reused every six years. If a storm does a lot of damage, its name is sometimes taken off the list. It is then replaced by a new name that starts with the same letter.

How Climate Change is Making Tropical Cyclones Worse

As mentioned above, warm water is fundamentally needed for a cyclone to form. Because climate change is heating up ocean waters and atmospheric temperature, hurricanes are getting and will continue to get worse.

From this National Geographic article Hurricane Florence's Rains May Be 50% Worse Thanks to Climate Change:

The catastrophic rains expected to accompany Hurricane Florence along the U.S. East Coast can be blamed squarely on climate change, new research shows. The rainfall is projected to be more than 50 percent worse than it would have been without global warming, a team of scientists say. The hurricane’s size is predicted to be about 50 miles (80 kilometers) wider for the same reason.

That reason: warmer ocean and atmospheric temperatures, caused by the warming Earth.

I know I hit on this with my climate change piece, but we are already witnessing the catastrophic effects of not taking climate change seriously. It will only continue to get worse. I realize that people may not want to confront such an existential and frightening issue, but it’s hard to ignore the facts when they’re presented in front to you.

At first glance, I can understand why it might feel like finger-wagging to say “climate change is going to make natural disasters worse!!” It probably seems hard to believe, but when you understand cyclones a bit better – and I hope this article helped! – it’s a bit easier to understand. 

In Conclusion

Cyclones are rotating, low-pressure thunderstorm systems that occur in the Atlantic basin. For a cyclone to occur, warm water and consistency winds are needed. Due to a heating climate, ocean waters are heating, which in turn leads to progressively worse cyclone systems.

Table of Contents

  1. My New Project: Science Sundays

  2. Science Sundays #1 – Vaccines

  3. Science Sundays #2 – Caffeine and Its Effects on The Body

  4. Science Sundays #3 – Genetically Modified Organisms (GMOs)

  5. Science Sundays #4 – Global Warming, Climate Change, or the Unnatural Heating of the Earth’s Climate Due to Human Activity & Negligence

  6. Science Sundays #5 – Evolution, Explained

  7. Science Sundays #6 – Tropical Cyclones: Hurricanes & Typhoons